Healthy, Sustainable Siding

It goes without saying that exterior siding should be weather, pest and fire resistant. It should last a long time to minimize maintenance and replacement costs. And it’s the only thing many of your neighbors will ever see of your home, so of course you want it to look nice too. Though traditional wood siding is a time-honored favorite for exterior cladding, wood brings a host of environmental and maintenance challenges. Wood is highly susceptible to pests and decay, which means that it has a shorter life span than other siding options, increasing the use of natural resources as well as maintenance and replacement costs.  

The durable and low-maintenance quality of vinyl makes it a popular alternative to wood siding or shingles. Its fire resistant nature, immunity to corrosion, and imperviousness to pests cannot be denied. But the benefits of vinyl (also known as Polyvinyl chloride or PVC) may not outweigh its environmental and health hazards.

According to the Healthy Building Network, PVC is the worst plastic from an environmental health perspective, posing great environmental and health hazards in its manufacture, product life and disposal. The consumer education and advocacy website tied to the award-winning documentary, Blue Vinyl (a film that explores and exposes the toxic lifecycle of PVC), states that PVC contains chemical stabilizers that leach, flake or outgas over time, raising risks of asthma and cancer. Further, PVC poses a great risk in waste incineration and building fires, as it releases deadly gases such as hydrogen chloride long before it ignites. As it burns, it emits toxic dioxin waste.

Happily, there are other siding alternatives that are also more durable and fire resistant than wood, yet don’t have the toxic side effects of vinyl. One such product is fiber cement siding.

Fiber cement is an extremely durable product that is highly resistant to everyday wear and tear. Fiber cement closely emulates the look of wood, but its physical properties provide several performance advantages. All wood and wood-based products absorb moisture, and the ensuing expansion places continuous stress on the material over time. More importantly, the subsequent growth of mold and fungus goes unnoticed until the damage requires expensive replacement. Fiber cement, in comparison, will not swell, warp or rot. The material also resists wood-boring insects, the damaging effects of oceanic salt spray and ultraviolet rays, and does not succumb to the stress of freeze-thaw cycles, so it can be used in many different climates.

Like wood, fiber cement must be primed and painted or stained. However, the material’s paint adherence properties reduce the frequency of re-painting, saving resources and money. Maintenance involves simply washing the exterior with a garden hose to remove dirt and debris as necessary.  

In addition to a longer lifespan (warranties on the product range from 30-50 years), fiber cement has several other environmentally responsible attributes. Its ingredients have relatively low environmental impact. It is most commonly manufactured using a mixture of cement, pulp fiber, sand, water and other additives. The pulp fiber is a renewable resource that can be sourced from sustainable forests. In recent years, some manufacturers have replaced sand with fly ash, a by-product from electric generation at coal-fired power plants. This has the added benefit of diverting fly-ash from the landfill.  
 
Build It Green, a non-profit promoting the use of greener building practices, maintains a directory of building product alternatives. For a list of suppliers of healthy, sustainable siding products, see Build It Green’s product directory at www.builditgreen.org/green-product-directory. Annette Hartsfield is a Build It Green project manager and grant writer.